There are a limited number of methods for modifying the density of flowable material such as liquids, foods, beverages, dairy, agricultural or non-food products where low and/or variable density results from for example entrained gas or dissolved gas. Gas entrainment or non-uniform density of a material creates packaging line problems which include insufficient fill levels or over filling such that consistency in filling is lost. Expansion of the material post filling may result in compromised seal integrity, foaming of the material or reduced shelf life due to gas entrainment. Further, gas entrainment may compromise uniformity of a food and beverage product after packaging thus contributing to rejection or re-call of the product.
Consistent fill levels and uniformity in a packaged material may be attained by the application of a vacuum, settling in large tanks or a reduction of packaging line or bottling operation speed. Combinations of those methods to modifying the density of the material may also be used.
A problem with these methods is that they increase the equipment needed and/or involve additional processes, are expensive and require production times to be increased.
Conventional ultrasonic baths have been utilised to modify the density of a wide variety of liquids on a small scale. The ultrasonic energy that is produced by the conventional ultrasound bath is in the form of a standing wave so that when, for example, a liquid is placed in the bath, the pattern of energy waves shows alternating zones in the liquid. In order to achieve a greater effect in terms of modifying the density of a material, the material needs to be moved relative to the standing wave that forms in the ultrasonic bath which can be impractical for large volumes of material.
Furthermore, conventional ultrasonic baths produce energy waves that dissipate very quickly with distance and do not propagate uniformly through flowable materials.
The present invention is predicated on the surprising discovery that the application of highly propagating ultrasonic energy to a flowable material modifies the density of that material.